Comparing Deprivation vs Vulnerability Index Performance Using Medicare Beneficiary Surgical Outcomes

Abstract

Importance: Health care researchers, professionals, payers, and policymakers are increasingly relying on publicly available composite indices of area-level socioeconomic deprivation to address health equity. Implications of index selection, however, are not well understood.

Objective: To compare the performance of 2 frequently used deprivation indices using policy-relevant outcomes among Medicare beneficiaries undergoing 3 common surgical procedures.

Design, setting, and participants: This cross-sectional study examined outcomes among Medicare beneficiaries (65 to 99 years old) undergoing 1 of 3 common surgical procedures (hip replacement, knee replacement, or coronary artery bypass grafting) between 2016 and 2019. Index discriminative performance was compared for beneficiaries residing in tracts with high- and low-deprivation levels (deciles) according to each index. Analyses were conducted between December 2022 and August 2023.

Main outcomes and measures: Tract-level deprivation was operationalized using 2020 releases of the area deprivation index (ADI) and the social vulnerability index (SVI). Binary outcomes were unplanned surgery, 30-day readmissions, and 30-day mortality. Multivariable logistic regression models, stratified by each index, accounted for beneficiary and hospital characteristics.

Results: A total of 2 433 603 Medicare beneficiaries (mean [SD] age, 73.8 [6.1] years; 1 412 968 female beneficiaries [58.1%]; 24 165 Asian [1.0%], 158 582 Black [6.5%], and 2 182 052 White [89.7%]) were included in analyses. According to both indices, beneficiaries residing in high-deprivation tracts had significantly greater adjusted odds of all outcomes for all procedures when compared with beneficiaries living in low-deprivation tracts. However, compared to ADI, SVI resulted in higher adjusted odds ratios (adjusted odds ratios, 1.17-1.31 for SVI vs 1.09-1.23 for ADI), significantly larger outcome rate differences (outcome rate difference, 0.07%-5.17% for SVI vs outcome rate difference, 0.05%-2.44% for ADI; 95% CIs excluded 0), and greater effect sizes (Cohen d, 0.076-0.546 for SVI vs 0.044-0.304 for ADI) for beneficiaries residing in high- vs low-deprivation tracts.

Conclusions and relevance: In this cross-sectional study of Medicare beneficiaries, SVI had significantly better discriminative performance-stratifying surgical outcomes over a wider range-than ADI for identifying and distinguishing between high- and low-deprivation tracts, as indexed by outcomes for common surgical procedures. Index selection requires careful consideration of index differences, index performance, and contextual factors surrounding use, especially when informing resource allocation and health care payment adjustment models to address health equity.

Figure 1.. Mean Index Score Comparisons for Tracts With Extreme Good and Poor Area Deprivation Index (ADI)-Social Vulnerability Index (SVI) Agreement

^aThe image illustrates the 8 census tract-level comparison groups with respect to the distribution of tracts by index decile score shown in eFigure 2a in Supplement 1. ^bTotal number of tracts within a comparison group decile, as noted first in the agreement definition (eg, 8372 tracts in comparison I; top ADI [10%] decile; eFigure 2a in Supplement 1). ^cGood index agreement was defined as index scores that differed by 0 to 1 decile. Poor index agreement was defined as index scores that differed by at least 6 deciles. ^dHigher mean index scores indicated higher deprivation levels. A population-weighted mean was used to aggregate ADI block group data to tract; ADI is a percentile ranking from 0 to 100. Mean SVI scores (percentile rankings from 0 to 1) were multiplied by 100 for comparison with ADI scores.

Figure 2.. Risk-Adjusted Outcomes for Medicare Beneficiaries Undergoing Common Surgical Procedures by Area Deprivation Index (ADI) and Social Vulnerability Index (SVI) Deprivation Deciles

Data Source: 2016 through 2019 Medicare hip replacement, knee replacement, and coronary artery bypass grafting (CABG) surgery. Deprivation scores were categorized by decile. Models were adjusted for age, sex, unplanned admission (30-day readmissions and 30-day mortality models), comorbidities, dual eligibility, year of surgery, hospital teaching status, and hospital nurse-to-patient ratio. All adjusted odds ratios comparing outcome rates among beneficiaries residing in tracts with the highest and lowest decile scores were significant (P < .001; Table 2). Small (Cohen d of 0.20 or higher to less than 0.50) to medium (Cohen d of 0.50 or higher to less than 0.80) effect sizes were found for highest-lowest index decile comparisons in A, B, D, and E.